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https://www.readbyqxmd.com/read/28937970/spectroscopy-and-enhanced-frequency-upconversion-in-nd-3-yb-3-codoped-tpo-glasses-energy-transfer-and-nir-to-visible-upconverter
#1
Mohd Azam, Vineet Kumar Rai, Deepak Kumar Mohanty
TeO2-Pb3O4 (TPO) glasses codoped with Nd(3+) and Yb(3+) ions have been fabricated by conventional melting technique. The absorption, emission and excitation spectra of the samples have been recorded. The optical band gap in both the doped/codoped glasses is found to be ∼3.31 eV. Judd-Ofelt analysis has been carried out by using the absorption spectrum of 0.8 mol% Nd(3+) doped glass to determine the radiative properties viz radiative transition probabilities, branching ratios, radiative lifetimes, quality factor and emission cross sections of some emitting levels for Nd(3+) ions...
September 22, 2017: Methods and Applications in Fluorescence
https://www.readbyqxmd.com/read/28937755/stability-and-superconductivity-of-k-p-compounds-under-pressure
#2
Yunxian Liu, Chao Wang, Xiangmu Kong, Defang Duan
We explore the phase diagram, structures, electron properties, and potential superconductivity of the K-P system at pressures of up to 200 GPa through unbiased structure searching techniques and first-principles calculations. Five stable chemical stoichiometries (K4P, K3P, K2P, KP, and KP2) have been theoretically predicted. In particular, P2 units or P-chains are uncovered in K2P, KP, and KP2 compounds with the existence of covalent bonds by analyzing the electron localization functions. And the Bader analysis demonstrates that charges transfer from K atoms to P atoms...
September 22, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28937743/rational-design-of-an-anticalin-type-sugar-binding-protein-using-a-genetically-encoded-boronate-side-chain
#3
Selvakumar Edwardraja, Andreas Eichinger, Ina Theobald, Carina Andrea Sommer, Andreas J Reichert, Arne Skerra
The molecular recognition of carbohydrates plays a fundamental role in many biological processes. However, the development of carbohydrate-binding reagents for biomedical research and use poses a challenge due to the generally poor affinity of proteins towards sugars in aqueous solution. Here, we describe the effective molecular recognition of pyranose monosaccharides (in particular, galactose and mannose) by a rationally designed protein receptor based on the human lipocalin scaffold (Anticalin). Complexation relies on reversible covalent cis-diol boronate diester formation with a genetically encoded L-boronophenylalanine (Bpa) residue which was incorporated as a non-natural amino acid at a sterically permissive position in the binding site of the Anticalin, as confirmed by X-ray crystallography...
September 22, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28937695/trinuclear-complexes-of-palladium-ii-with-chalcogenated-n-heterocyclic-carbenes-catalysis-of-selective-nitrile-primary-amide-interconversion-and-sonogashira-coupling
#4
Pooja Dubey, Sonu Gupta, Ajai K Singh
3-Methyl-1-(2-(phenylthio/seleno)ethyl)-1H-benzo[d]imidazol-3-ium iodide (L1/L2), a precursor of sulfated/selenated N-heterocyclic carbene, was synthesized by the reaction of benzimidazole with 1,2-dichloroethane followed by treatment with PhS/SeNa and MeI. The reaction of L1/L2 with Ag2O followed by treatment with [Pd(CH3CN)2Cl2] (metal to ligand ratio 3 : 2), i.e. transmetallation, resulted in trinuclear palladium(ii) complexes [Pd3(L1/L2-HI)2(CH3CN)Cl6] (1-2). The complexes were characterized with (1)H, (13)C{(1)H} and (77)Se{(1)H} NMR (2 only), elemental analyses, HR-MS and single-crystal X-ray diffraction...
September 22, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28937678/anionic-silicate-organic-frameworks-constructed-from-hexacoordinate-silicon-centres
#5
Jérôme Roeser, Dragica Prill, Michael J Bojdys, Pierre Fayon, Abbie Trewin, Andrew N Fitch, Martin U Schmidt, Arne Thomas
Crystalline frameworks composed of hexacoordinate silicon species have thus far only been observed in a few high pressure silicate phases. By implementing reversible Si-O chemistry for the crystallization of covalent organic frameworks, we demonstrate the simple one-pot synthesis of silicate organic frameworks based on octahedral dianionic SiO6 building units. Clear evidence of the hexacoordinate environment around the silicon atoms is given by (29)Si nuclear magnetic resonance analysis. Characterization by high-resolution powder X-ray diffraction, density functional theory calculation and analysis of the pair-distribution function showed that those anionic frameworks-M2[Si(C16H10O4)1...
October 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28937645/bioelectrochemical-detection-of-mycobacterium-tuberculosis-esat-6-in-an-antibody-based-biomicrosystem
#6
Danna Sepulveda, Miguel A Aroca, Andres Varela, Patricia Del Portillo, Johann F Osma
Bioelectrochemical sensing of Mycobacterium tuberculosis through electro-immunosensors is a promising technique to detect relevant analytes. In general, immunosensors require the formation of organic assemblies by the adsorption of molecular constituents. Moreover, they depend on the correct immobilization of the bio-recognition element in the biosensor. These procedures cannot be easily monitored without the use of invasive methods. In this work, an impedance analysis technique was used, as a non-invasive method, to measure and differentiate the manufacturing stages of the sensors...
September 22, 2017: Sensors
https://www.readbyqxmd.com/read/28937637/adsorption-mechanisms-of-dodecylbenzene-sulfonic-acid-by-corn-straw-and-poplar-leaf-biochars
#7
Nan Zhao, Xixiang Yang, Jing Zhang, Ling Zhu, Yizhong Lv
Biochar is an eco-friendly, renewable, and cost-effective material that can be used as an adsorbent for the remediation of contaminated environments. In this paper, two types of biochar were prepared through corn straw and poplar leaf pyrolysis at 300 °C and 700 °C (C300, C700, P300, P700). Brunaer-Emmett-Teller N₂ surface area, scanning electron microscope, elemental analysis, and infrared spectra were used to characterize their structures. These biochars were then used as adsorbents for the adsorption of dodecylbenzene sulfonic acid (DBSA)...
September 22, 2017: Materials
https://www.readbyqxmd.com/read/28936507/a-pyrene-modified-cobalt-salophen-complex-immobilized-on-multiwalled-carbon-nanotubes-acting-as-a-precursor-for-efficient-electrocatalytic-water-oxidation
#8
Ting-Ting Li, Jinjie Qian, Qianqian Zhou, Jian-Li Lin, Yue-Qing Zheng
Immobilization of earth-abundant water oxidation catalysts (WOCs) on carbon supports to produce functional electrodes for electrochemical water splitting is a crucial approach for future clean energy production. Herein we report the non-covalent immobilization of a pyrene-bearing cobalt(ii) Schiff base complex (2) on the surface of multiwalled carbon nanotubes (MWCNTs) to form a hybrid anode for electrocatalytic water oxidation. The 2/MWCNT anode displayed excellent catalytic activity and durability in neutral aqueous solution, and a catalytic current density of 1...
September 22, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28936332/designing-brighter-near-infrared-fluorescent-proteins-insights-from-structural-and-biochemical-studies
#9
Mikhail Baloban, Daria M Shcherbakova, Sergei Pletnev, Vladimir Z Pletnev, J Clark Lagarias, Vladislav V Verkhusha
Brighter near-infrared (NIR) fluorescent proteins (FPs) are required for multicolor microscopy and deep-tissue imaging. Here, we present structural and biochemical analyses of three monomeric, spectrally distinct phytochrome-based NIR FPs, termed miRFPs. The miRFPs are closely related and differ by only a few amino acids, which define their molecular brightness, brightness in mammalian cells, and spectral properties. We have identified the residues responsible for the spectral red-shift, revealed a new chromophore bound simultaneously to two cysteine residues in the PAS and GAF domains in blue-shifted NIR FPs, and uncovered the importance of amino acid residues in the N-terminus of NIR FPs for their molecular and cellular brightness...
June 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28935257/tetrac-conjugated-polymersomes-for-integrin-targeted-delivery-of-camptothecin-to-colon-adenocarcinoma-in-vitro-and-in-vivo
#10
Mona Alibolandi, Rouhollah Rezvani, Sara Amel Farzad, Seyed Mohammad Taghdisi, Khalil Abnous, Mohammad Ramezani
In this study, we prepared tetraiodothyroacetic acid (tetrac) conjugated PEG-PLGA polymersomes for the targeted delivery of camptothecin to colon adenocarcinoma. Tetrac, which binds to integrin αvβ3 with high affinity and specificity, was covalently conjugated to the surface of the PEGylated polymersomal formulation of camptothecin (CPT). The hydrodynamic and morphological properties of the prepared system were evaluated using TEM (transmission electron microscopy), SEM (scanning electron microscopy) and DLS (dynamic light scattering) experiments...
September 18, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28935112/a-pipeline-for-studying-and-engineering-single-subunit-oligosaccharyltransferases
#11
Thapakorn Jaroentomeechai, Xiaolu Zheng, Jasmine Hershewe, Jessica C Stark, Michael C Jewett, Matthew P DeLisa
Asparagine-linked (N-linked) protein glycosylation is one of the most abundant types of posttranslational modification, occurring in all domains of life. The central enzyme in N-linked glycosylation is the oligosaccharyltransferase (OST), which catalyzes the covalent attachment of preassembled glycans to specific asparagine residues in target proteins. Whereas in higher eukaryotes the OST is comprised of eight different membrane proteins, of which the catalytic subunit is STT3, in kinetoplastids and prokaryotes the OST is a monomeric enzyme bearing homology to STT3...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28934551/polymer-conjugation-to-enhance-cellulase-activity-and-preserve-thermal-and-functional-stability
#12
Thaiesha A Wright, Melissa Lucius Dougherty, Benjamin Schmitz, Kevin M Burridge, Katherine Makaroff, Jamie M Stewart, Henry D Fischesser, Jerry T Shepherd, Jason A Berberich, Dominik Konkolewicz, Richard C Page
A thermophilic cellulase, FnCel5a, from Fervidobacterium nodosum was conjugated with various functional polymers including cationic, anionic, and strongly and weakly hydrogen bonding polymers. The activity of FnCel5a toward a high molecular weight carboxymethyl cellulose substrate was enhanced by polymer conjugation. Activity enhancements of 50% or greater observed for acrylamide and mixed N,N-dimethyl acrylamide/2-(N,N-dimethylamino)ethyl methacrylate polymers suggesting that the greatest enhancements were caused by polymers capable of non-covalent interactions with the substrate...
September 21, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28934117/new-zno-cardanol-porphyrin-composite-nanomaterials-with-enhanced-photocatalytic-capability-under-solar-light-irradiation
#13
Viviane Gomes Pereira Ribeiro, Ana Maria Pereira Marcelo, Kássia Teixeira da Silva, Fernando Luiz Firmino da Silva, João Paulo Ferreira Mota, João Paulo Costa do Nascimento, Antonio Sérgio Bezerra Sombra, Claudenilson da Silva Clemente, Giuseppe Mele, Luigi Carbone, Selma Elaine Mazzetto
This work describes the synthesis, characterization, and photocatalytic activity of new composite nanomaterials based on ZnO nanostructures impregnated by lipophlilic porphyrins derived from cashew nut shell liquid (CNSL). The obtained nanomaterials were characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and steady-state photoluminescence spectra (PL). The results confirm nanostructures showing average diameter of 55 nm and an improved absorption in the visible region...
September 21, 2017: Materials
https://www.readbyqxmd.com/read/28933823/two-color-810-nm-sted-nanoscopy-of-living-cells-with-endogenous-snap-tagged-fusion-proteins
#14
Alexey N Butkevich, Haisen Ta, Michael Ratz, Stefan Stold, Stefan Jakobs, Vladimir N Belov, Stefan W Hell
A 810 nm STED nanoscopy setup and an appropriate combination of two fluorescent dyes (Si-rhodamine 680SiR and carbopyronine 610CP) have been developed for near-IR live-cell superresolution imaging. Vimentin endogenously tagged using the CRISPR/Cas9 approach with the SNAP-tag, together with a non-covalent tubulin label, provided reliable and cell-to-cell reproducible dual-color confocal and STED imaging of the cytoskeleton in living cells.
September 21, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28933754/the-positive-correlation-of-the-enhanced-immune-response-to-pcv2-subunit-vaccine-by-conjugation-of-chitosan-oligosaccharide-with-the-deacetylation-degree
#15
Guiqiang Zhang, Gong Cheng, Peiyuan Jia, Siming Jiao, Cui Feng, Tao Hu, Hongtao Liu, Yuguang Du
Chitosan oligosaccharides (COS), the degraded products of chitosan, have been demonstrated to have versatile biological functions. In primary studies, it has displayed significant adjuvant effects when mixed with other vaccines. In this study, chitosan oligosaccharides with different deacetylation degrees were prepared and conjugated to porcine circovirus type 2 (PCV2) subunit vaccine to enhance its immunogenicity. The vaccine conjugates were designed by the covalent linkage of COSs to PCV2 molecules and administered to BALB/c mice three times at two-week intervals...
July 26, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28933740/synthesis-characterization-and-in-vitro-evaluation-of-a-novel-glycol-chitosan-edta-conjugate-to-inhibit-aminopeptidase-mediated-degradation-of-thymopoietin-oligopeptides
#16
Jiao Feng, Yan Chen, Feng Li, Lili Cui, Nianqiu Shi, Wei Kong, Yong Zhang
In this study, a novel conjugate consisting of glycol chitosan (GCS) and ethylene diamine tetraacetic acid (EDTA) was synthesized and characterized in terms of conjugation and heavy metal ion chelating capacity. Moreover, its potential application as a metalloenzyme inhibitor was evaluated with three thymopoietin oligopeptides in the presence of leucine aminopeptidase. The results from FTIR and NMR spectra revealed that the covalent attachment of EDTA to GCS was achieved by the formation of amide bonds between the carboxylic acid group of EDTA and amino groups of GCS...
July 26, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28933585/oncogenic-ras-induced-downregulation-of-atg12-is-required-for-survival-of-malignant-intestinal-epithelial-cells
#17
Byong Hoon Yoo, Iman Aftab Khan, Ananda Koomson, Pramod Gowda, Takehiko Sasazuki, Senji Shirasawa, Shashi Gujar, Kirill Rosen
Activating mutations of RAS GTPase contribute to the progression of many cancers, including colorectal carcinoma. So far, attempts to develop treatments of mutant RAS-carrying cancers have been unsuccessful owing to insufficient understanding of the salient mechanisms of RAS signalling. We found that RAS downregulates the protein ATG12 in colon cancer cells. ATG12 is a mediator of autophagy, a process of degradation and reutilization of cellular components. In addition, ATG12 can kill cells via autophagy-independent mechanisms...
September 21, 2017: Autophagy
https://www.readbyqxmd.com/read/28933545/a-first-principles-chemical-bonding-study-of-manganese-carbodiimide-mnncn-as-compared-to-manganese-oxide-mno
#18
Ryky Nelson, Philipp M Konze, Richard Dronskowski
We have performed an in-depth study of the chemical bonding in manganese oxide (MnO) and carbodiimide (MnNCN) from correlated spin-polarized density-functional calculations. The chemical-bonding data were produced using the LOBSTER package which has recently been enabled to process PAW-based output from Quantum ESPRESSO. Our results show that the ground states of MnO and MnNCN are similar, namely, antiferromagnetic structures whose axes are the MnO cubic [111] and the MnNCN hexagonal [001] axis, in agreement with experimental results...
September 21, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28933535/development-of-visible-light-induced-photoelectrochemical-platform-based-on-cyclometalated-iridium-iii-complex-for-bioanalysis
#19
Chunxiang Li, Weisen Lu, Ming Zhu, Bo Tang
The performance of the photoelectrochemical (PEC) bioanalysis relies closely on the properties of the usedphotoactive species. In this study, a visible-light induced PEC active species, [(C6)2Ir(dcbpy)]+PF6- (C6 = coumarin 6, dcbpy = 2,2'-bipyridine-4,4'-dicarboxylic acid) was prepared based on C6 with the stronger absorbance in the visible region. The as-prepared complex was characterized by 1H NMR,UV-visible absorption and cyclic voltammetry. It exhibits intense absorption in visible region at 480 nm with a molar extinction coefficient (ε) of more 40000 M-1cm-1, which is approximately twice that of Ru(bpy)32+...
September 21, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28933282/molecular-mechanisms-of-epigenetic-regulators-as-activatable-targets-in-cancer-theranostics
#20
Yinglu Li, Zhiming Li, Wei-Guo Zhu
Epigenetics is defined as somatically inheritable changes that are not accompanied by alterations in DNA sequence. Epigenetics encompasses DNA methylation, covalent histone modifications, non-coding RNA as well as nucleosome remodeling. Notably, abnormal epigenetic changes play a critical role in cancer development including malignant transformation, metastasis, prognosis, drug resistance and tumor recurrence, which can provide effective targets for cancer prognosis, diagnosis and therapy. Understanding these changes provide effective means for cancer diagnosis and druggable targets for better clinical applications...
September 20, 2017: Current Medicinal Chemistry
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